Self-doped Porous Carbon Research Articles

NiCo-MOFs derived carbon matrix composites: A promising electrode construction for high-performance supercapacitors

Metal-organic frameworks (MOFs) are great precursors and templates for preparing adsorbents, catalysts and electrodes due to the porous structure and high specific surface area. We report a promising approach to prepare nanocrystalline Co, Ni sulfides (CNS) embedded and N self-doped porous carbon (NPC) matrix composites derived from NiCo-MOFs. The CNS@NPC composite was investigated as electrodes for hybrid supercapacitors (HSCs). The prepared electrode achieved specific capacitance of 2789 F g−1 at 1 A/g, and high capacitance retention of 88.93% after 6000 galvanostatic charge–discharge (GCD) cycles under 10 A/g. The HSC structured with CNS@NPC//AC achieved an energy density of 46.79 Wh kg−1 at power density of 800 W kg−1. Meanwhile, specific capacitance of 131.56 F g−1 at 1 A/g and capacitance retention of 99.17% over 6000 GCD cycles under 3 A/g were obtained. Space confinement by the carbon skeleton effectively prevents the aggregation of the redox active nanocrystalline and improves the durability of the electrode. Meanwhile, the carbon skeleton provides abundant charge transfer channels to enhance the redox reaction. In other words, synergistic effect of the carbon skeleton and the active redox nanocrystalline significantly improves the electrochemical properties of the composite.

O-N-S self-doped porous fusiform carbon particles derived from hair for high-performance supercapacitors

O-N-S self-doped porous fusiform carbon particles derived from hair for high-performance supercapacitors

Tetra-heteroatom self-doped and hierarchical porous carbon toward high-performance zinc-ion hybrid supercapacitors

Porous carbon has been reported as a promising cathode material for zinc-ion hybrid supercapacitors (ZHSCs). However, it is limited by inferior ionic diffusion and insufficient active adsorption sites during charge/discharge process. Herein, a tetra-heteroatom self-doped and hierarchical porous carbon material (PMAC700-3) derived from paper mulberry has been fabricated through facile carbonization and activation process. Owing to the high tetra-heteroatom content (∼15.76 % atomic ratio of N, O, S, P), hierarchical porous structure, and specific surface area (1736.1 m2 g−1), the PMAC700-3 cathode exhibits considerable ionic diffusion, abundant active adsorption sites, and superior electric conductivity, thereby significantly improving the electrochemical performance of ZHSCs. The ZHSC based on PMAC700-3 cathode delivers an excellent specific capacitance of 240.7 F g−1 at 0.5 A/g, energy density of 108.3 Wh kg−1, power density of 450 W kg−1, along with exceptional cycling stability (97.7 % capacity retention after 10,000 cycles at 10 A/g). Under high mass loading of 39.09 mg cm−2, the areal capacitance of PMAC700-3 based ZHSC reaches up to 4.26 F cm−2. This work provides a universal strategy to achieve multiple heteroatoms self-doped porous carbon materials from biomass for ZHSCs.

N, O self-doped porous carbon derived from distiller's grains for high performance supercapacitors

Improving the charge storage capacity of carbon materials derived from biomass waste is an important aspect for their practical applications as supercapacitor electrodes. A reasonable design of heteroatom-doped carbon materials derived from industrial distiller 's grains can significantly enhance the efficacy of the supercapacitor. Therefore, a distiller's grain-derived (DG) N/O self-doped activated carbon (DG-5-X) was developed for use in supercapacitors. The incorporation of heteroatoms into porous carbon materials can facilitate enhanced electrode-to-electrolyte interaction resulting in improved pseudo-capacitance, thereby enhancing the electrochemical performance. A remarkable 345.2 F g−1 specific capacitance was demonstrated in a three-electrode system employing DG-5–6 (with N and O heteroatom contents of 1.62 % and 19.27 %, respectively) as the electrode in a 6 M KOH electrolyte solution (at 1 A g−1). In addition, a symmetric coin-type supercapacitor (SSC) device was developed, which demonstrated excellent cyclic stability and a competitive energy density of 12.2 Wh kg−1 (at a 348.8 W kg−1 power density). SSC retained 95.6 % of the capacitance after 5000 cycles at 5 A g−1. In summary, the distiller’s grains as a raw material show great potential in the development of carbon-based energy storage materials that display outstanding electrochemical performance.

Enhancement of Electrocatalytic Oxygen Reduction Reaction and Oxygen Evolution Reaction by Introducing Lanthanum Species in the Carbon Shell.

The development of cost-effective non-noble metal electrocatalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) opens up the possibility for sustainable energy systems. Herein, we report a surface overcoating strategy with lanthanum organic complex (La-OC) as the precursor to prepare lanthanum species (La-SPc) encapsulated in nitrogen, fluorine, and sulfur self-doped porous carbon (NFS-PC) composites (La-SPc@NFS-PC) for efficient ORR and OER. The La-SPc is introduced not only as a promoter to increase the electrochemical stability of the La-SPc@NFS-PC catalysts but also to tailor the electronic structure of NFS-PC due to the unique electrochemical properties of La-SPc. In addition, the integration of La-SPc and NFS-PC can improve the electronic conductivity of composites by inducing electron redistribution and lowering the band gap, which is advantageous in enhancing the kinetics of charge transfer. Simultaneously, benefiting from the optimized porous structure and positive cooperation of La-SPc with NFS-PC shells, the obtained La-SPc@NFS-PC-3 delivers robust bifunctional ORR/OER activities and stabilities. More importantly, the Zn-air battery (ZAB) assembled with La-SPc@NFS-PC-3 demonstrates an outstanding power density (181.1 mW cm-2) and long cycling life, outperforming the commercial Pt/C. This work offers a rational approach to preparing high-efficiency rare-earth-based catalysts and provides potential applications in ZABs.

One-step fabrication of N/O self-doped porous carbon derived from 2-MeIM for high-performance supercapacitor electrode

Doping engineering is a high-efficiency strategy to introduce heteroatom species and modify the surface electronic structures of porous carbon materials. However, the conventional doping strategies for porous carbons usually involve with either complicated fabrication processes or difficulty in quality control. Herein, nitrogen‑oxygen self-doped porous carbons (NOPCs) with adjustable structure are prepared by a facile one-step process of direct carbonization/activation the mixture of 2-methylimidazole (2-MeIM) and KOH. The as-prepared NOPCs possess hierarchical porous structure with interconnected micro-/meso-/macropores, high specific surface area (2900 m2 g−1), large pore volume (1.2 cm3 g−1) and high N,O heteroatoms level (26.8 at.% in total), which exhibit ultra-high specific capacitance of 424.2 F g−1 at 1.0 A g−1 in a three-electrode system in 2 M KOH electrolyte and 173.4 F g−1 at 1.0 A g−1 in a two-electrode system in EMIMBF4 ionic liquid electrolyte. Impressively, the symmetric supercapacitor based on NOPC exhibits a wide operating voltage window up to 3 V, a high energy density of 56.4 Wh kg−1 at a power density of 373.6 W kg−1, excellent rate performance with the retention of ~76.2 % from 1.0 to 100 A g−1, and splendid cycling stability with only 0.0011 % capacity fading per cycle within 10,000 loops. Consequently, the one-step carbonization/activation strategy with commercial-available 2-MeIM as raw material is promising for mass production of high performance NOPC materials.

Flexible asymmetric supercapacitor based on Hyphaene fruit shell-derived multi-heteroatom doped carbon and NiMoO4@NiCo2O4 hybrid structure electrodes

In accordance with ecological strategies for the production of renewable energy storage systems, herein, starting from the Hyphaene fruit shell (HFS) as a new carbon precursor, multi-heteroatom (O, N, S, P, and Si) self-doped porous carbon was successfully synthesized through carbonization and chemical activation (KOH) processes. The obtained honeycomb-like carbon structure (HFSC2) as negative electrode exhibited excellent electrochemical performance with high cycling stability and high specific capacitance of 337 F g−1 in 3 M KOH electrolyte solution. Meanwhile, the NiMoO4@NiCo2O4 hybrid nanostructure as a positive electrode was prepared through a simple two-step hydrothermal method followed by the annealing process. The NiMoO4/NiCo2O4 on Ni foam exhibits a very high specific capacitance of 1582 F g−1 at a current density of 0.5 A g−1 and excellent cycling stability of 82% after 3000 cycles. Further, for the practical application, the synthesized asymmetric all-solid-state supercapacitor offered high specific capacitance of 63.38 F g−1 (360.26 mF cm−2), a high energy density of 28.5 Wh kg−1 and a high-power density of 3800 W kg−1 at 14.8 Wh kg−1 within a voltage window of 0–1.8 V. These prominent electrochemical performances suggest that Hyphaene fruit shell-derived multi-heteroatom carbon and NiMoO4@NiCo2O4 hybrid electrodes have considerable applications in the field of energy storage technologies.

Acidified Nitrogen Self-Doped Porous Carbon with Superprotonic Conduction for Applications in Solid-State Proton Battery.

Solid proton electrolytes play a crucial role in various electrochemical energy storage and conversion devices. However, the development of fast proton conducting solid proton electrolytes at ambient conditions remains a significant challenge. In this study, a novel acidified nitrogen self-doped porous carbon material is presented that demonstrates exceptional superprotonic conduction for applications in solid-state proton battery. The material, designated as MSA@ZIF-8-C, is synthesized through the acidification of nitrogen-doped porous carbon, specifically by integrating methanesulfonic acid (MSA) into zeolitic imidazolate framework-derived nitrogen self-doped porous carbons (ZIF-8-C). This study reveals that MSA@ZIF-8-C achieves a record-high proton conductivity beyond 10-2 Scm-1 at ambient condition, along with good long-term stability, positioning it as a cutting-edge alternative solid proton electrolyte to the default aqueous H2 SO4 electrolyte in proton batteries.

Facile fabrication of magnesium-enriched porous carbon for highly active and stable isomerization of glucose in water

The endogenous MgO in-situ self-doped porous carbon (MgO@C) was fabricated from reliable magnesium citrate by a facile one-step pyrolysis process. Up to ∼60 wt% active magnesium oxide could be successfully embedded into the carbon skeleton with uniformly distributed MgO nanoparticles. The characterization analyses suggested that MgO@C had a “sand rose” structure with a large surface area, uniform pore-size distribution and small MgO crystal size. The MgO@C showed a high catalytic ability with a maximum fructose yield of 31.2% and selectivity of 86.2% from glucose isomerization in water at 85 °C within 60 min, which was better than that of the pure MgO and MgO supported on porous carbon (MgO/C). Moreover, the activation energy of glucose-fructose over MgO@C was calculated to be 54.20 kJ⋅mol−1, the value was less than that of MgO and MgO/C. The excellent catalytic activity was closely related to the moderate catalyst basicity, which was mainly caused by the smaller crystal size of magnesium oxide due to the confinement effect of porous carbon. More significantly, the as-prepared MgO@C exhibited good tolerability under high substrate concentrations (20 wt%), and could maintain good reusability without a serious decrease in activity during five cycles.

Enhanced conversion of superoxide radical to singlet oxygen in peroxymonosulfate activation by metal-organic frameworks derived heteroatoms dual-doped porous carbon catalyst

The activation of persulfate technology using carbon-based materials doped with heteroatoms has been extensively researched for the elimination of refractory pollutants in wastewater. In this study, metal-organic frameworks were utilized as precursors to synthesize P, N dual-doped carbon material (PNC), which was employed to activate peroxymonosulfate (PMS) for the degradation of tetracycline hydrochloride (TCH). The results demonstrated a 90.2% removal efficiency of total organic carbon within 60 min. The significant increase of surface defects on the nitrogen self-doped porous carbon materials anchored with phosphorus promoted the conversion of superoxide radical to singlet oxygen during PMS activation, which was identified as the key active species of PNC/PMS system. Additionally, the enhanced direct electron transfer also facilitated the degradation of TCH. Consequently, TCH was successfully degraded into nontoxic and harmless inorganic small molecules. The findings of this research provide valuable insights into improving the performance of heteroatom-doped carbon materials for pollutant degradation by activating PMS and transforming the non-radical pathway. The results highlight the potential of metal-organic frameworks derived heteroatoms dual-doped porous carbon catalysts for the development of advanced treatment technologies in wastewater treatment.

Green synthesis of nitrogen self-doped porous carbons from waste garlic peels for high-performance supercapacitor applications

Based on the biological structure of biomass materials, the preparation of carbon materials with special pore structures and rich surface groups is an important route in the development of new carbon materials for electrodes. In this work, a nitrogen self-doped carbon with unique tubular channel structures was synthesized from garlic peels for the high-performance supercapacitor electrode application. The mild KHCO3 was selected as the activator and therefore the biological structure of garlic peels is well preserved, showing a large number of long tubular channels with a diameter of around 50 nm. It was found that a nitrogen self-doped porous carbon material (SPC-4KC) with a nitrogen relative content of 1.77% and a large specific surface area of 1993.73 m2 g−1 was formed at 800 ℃ at a KHCO3/SPC mass ratio of 4:1. Using as the electrode material, the mass-specific capacitance of the SPC-4KC-based electrode reached 303.38 F g−1 at a current density of 1 A g−1 in the three-electrode system. In the two-electrode system, when the energy density is 7.42 W h kg−1, the power density is 314.33 W kg−1. Also, the material exhibits excellent cycle stability, with a capacitance retention of 94.87% after 5000 cycles at a current density of 10 A g−1.

Biomass derived N/O self-doped porous carbon for advanced supercapacitor electrodes

To satisfy the practical needs of the sustainability and industrialization of supercapacitors, it is essential to maintain good electrochemical performance at high mass loading above the commercial levels (10 mg cm−2). Herein, a unique 3D porous carbon with high mass loading is successfully prepared from Linum usitatissimum L. stem via a simple route of high temperature carbonization and subsequent KOH activation. The as-prepared porous carbon displays rich N/O heteroatoms, hierarchical porous, and interconnected vertical channels, which enable fast electron/ion transport and afford additional capacitance. These characteristics give the resultant carbon high capacitances of 434/245 F g−1 at 1/50 A g−1. Importantly, the as-prepared carbon can achieve mass loadings of 20 mg cm−2 and maintain decent electrochemical performance at this mass loadings, owing to short electron/ion transfer pathway as well as sufficient active sites. Specifically, the assembled symmetric supercapacitor delivers superior areal capacitance of 3.7 F cm−1 at 1 A g−1 and remarkably capacitance retention of 2.5 F cm−1 at 5 A g−1 under 20 mg cm−1. This work enlightens a sustainable and facile way for constructure advanced electrode material.

Cistanches herba residues derived nitrogen and oxygen self-doped porous carbon for high performance supercapacitor

Cistanches herba residues are successfully employed as starting materials to prepare porous carbon through pre-carbonization and KOH activation method. The effects of pre-carbonization, KOH activation, and pre-carbonization temperature are investigated. The optimal structure of as-prepared carbon has abundant micropores, high specific surface area (2767.2 m2 g−1), good affinity for electrolyte, and high content of self-doped O (29.09%) and N (1.37%). The supercapacitors constructed with the as-prepared carbon materials are able to exhibit good specific capacitance of 360.26 F g−1 at 1.0 A g–1 and 191.3 F g−1 at 100 A g–1 in 6.0 mol L−1 KOH electrolyte. Moreover, the as-prepared carbon-based supercapacitors also display good energy density of 21.72 Wh kg−1 (at 250 W kg −1) and achieve 100% specific capacitance retention after 13,000 cycles at 10 A g−1 in 1.0 mol L−1 H2SO4 electrolyte. Overall, this research presents a new avenue for high-value utilization of traditional Chinese medicine residues.

Nitrogen self-doped porous lamellar carbon with superior electrochemical performance

A novel nitrogen self-doped porous lamellar carbon materials were prepared by pyrolysis method, in which metal-free phthalocyanine used as a carbon source, and nanosized SiO2 and SWCNTs used as templates at the same time. The mesoporous structure is contributed by the nanosized SiO2 self-sacrificing template, and the microporous structure is produced by pyrolysis of Pc/SWCNTs. By adjusting the ratio between SWCNTs, nanosized SiO2, and phthalocyanine, the microscopic morphology and the electrochemical performance of porous carbon materials can be regulated. Benefit from its superior pore structure and large specific surface area, the nitrogen self-doped porous lamellar carbon materials show excellent electrochemical performance. When the mass ratio of the three was Pc/SWCNTs/SiO2 = 1:0.05:0.5, the nitrogen self-doped porous lamellar carbon material shows the largest specific capacity of 283.9 F/g at 1 A g−1 as a supercapacitor anode material. And after 5000 cycles, the composite material still maintained a specific capacity of 88.7 %, demonstrating excellent stability. The specific capacity under the two-electrode system of Sample 3 is 260.36 F/g, showing high energy density and power density (36.2 Wh/kg, 1041.2 W/kg). Therefore, this nitrogen self-doped porous lamellar carbon material has potential value as a supercapacitor anode material.

Preparation of high performance supercapacitors with nitrogen and oxygen self-doped porous carbon derived from wintersweet-fruit-shell

In this work, seedless wintersweet-fruit-shell was selected as carbon precursors, carbonized and labeled as WFC. WFC was activated by different proportions of KOH, the product was denoted as WFC-X (X = 1, 2, 3, 4 stand for the mass ratio between KOH and WFC). The morphology and structure of WFC and WFC-X were characterized by SEM and TEM. The crystallization of different materials were characterized by XRD and Raman.The electrochemical properties of WFC and WFC-X were investigated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. Among these materials, WFC-2 has the best electrochemical performance. It has the largest specific surface area (1489.31 m2 g−1). The specific capacitance of WFC-2 can achieve 433 F g−1, it has a capacitance retention rate of 95.20% after 5000 charge and discharge cycles. In order to more comprehensively test the electrochemical performance of WFC-2, a symmetrical supercapacitor was assembled using WFC-2. The assembled WFC-2//WFC-2 symmetric supercapacitor has been tested in 6 M KOH and 1 M Na2SO4 as the electrolyte. When the power density is 350 W kg−1, the energy density can get 14.07 Wh Kg−1 in 6 M KOH electrolyte. The symmetric supercapacitor has a capacitance retention rate of 92.36% and a coulomb efficiency of 96.55% after 5000 charges and discharges. At 1 M Na2SO4 electrolyte, when the power density is 500 W kg−1, the energy density can reach 8.33 Wh Kg−1. The symmetric supercapacitor has a capacitance retention rate of 92.44% and a coulomb efficiency of 98.11% after 5000 charge and discharge cycles. WFC-2 may be a good electrode material for supercapacitor due to its excellent electrochemical properties.

Preparation of S self-doped porous carbon nanospheres as ORR catalysts derived from block copolymer grafted S group

In order to increase the activity and decrease the cost of oxygen reduction reaction (ORR) catalyst, S self-doped porous carbon nanospheres ORR catalyst was prepared by pyrolyzing the block copolymer F127 grafted with 3-mercapto-propanoicaci. The composition and microstructure were characterized and its electrochemical performance was also investigated in O2-saturated 0.1 M KOH solutions. The results showed that, among all the obtained samples, C-S-750 had a porous carbon nanosphere structure with the doped sulfur of 7.08 at % and a maximum specific surface area of 776.3 m2/g. The onset potential, half-wave potential and limiting current density of C-S-750 were 0.92 V (versus RHE) and 0.80 V (versus RHE) and 5.77 mA/cm2@0.45 V in O2-saturated 0.1 M KOH solution, respectively, which were close to that of commercial 20% Pt/C catalysts. This provides a new way to introduce and increase the doped heteroatom in metal-free ORR catalysts.

Nitrogen self-doped porous carbon based on sunflower seed hulls as excellent double anodes for potassium/sodium ion batteries

Nitrogen self-doped porous carbon based on sunflower seed hulls as excellent double anodes for potassium/sodium ion batteries

From pollutant to high-performance supercapacitor: Semi-coking wastewater derived N–O–S self-doped porous carbon

Heteroatom-doped porous carbon has attracted enormous attention in fabricating high-performance supercapacitors. However, designing heteroatoms containing carbon materials through an eco-friendly and cost-effective route remains challenging. In this work, N-O-S self-doped porous carbon materials are prepared from semi-coking wastewater-based phenolic resin (SWPR) via a simple Na2CO3 activation strategy. The abundant phenols, NH4+, and SO42- in semi-coking wastewater endows the versatile N, O, and S doping in porous carbon material, remarkably enhancing its conductivity. The optimal SWPR-700–2.5 porous carbon material is obtained at an activation temperature of 700 °C and a mass ratio of 2.5:1 for SWPR: Na2CO3. The symmetrical supercapacitor is assembled with SWPR-700–2.5, exhibiting a high specific capacitance of 170.5 F g−1 at 0.5 A g−1, with a high energy density of 5.92 Wh kg−1 at 124.9 W kg−1. After 10,000 cycles, the Coulombic efficiency and capacity retention are 100% and 99.4%, respectively, at a current density of 20 A g−1. The excellent performance of SWPR-700–2.5 based capacitor is attributed to the porous structure with a large specific surface area (718 m2 g−1) and abundant N-O-S self-doping (2.739 at% N, 8.627 at% O and 1.378 at% S). This study provides a simple route to prepare N-O-S self-doped porous carbon for supercapacitors and pushes forward the advancement of semi-coking wastewater treatment.

In situ construction of metal-organic frameworks on chitosan-derived nitrogen self-doped porous carbon for high-performance supercapacitors

The intelligent use of regenerable and degradable biomass materials to substitute the synthetic materials can bring huge economic benefits and environmental improvements. In addition, metal-organic framework (MOF) based cathode materials are becoming a research hotspot for supercapacitors. Here, Co nanoparticle-modified nitrogen self-doped porous carbonized chitosan aerogel (CCA-Co) precursors were prepared by sol-gel, freeze-drying technique and carbonization process using biomass chitosan particles and cobalt compounds as raw materials. Then the layered composite (CCA-Co@MOF) was obtained by growing Co-doped Ni MOF (Co-Ni MOF) with CCA-Co precursor as the carrier. Notably, the presence of Co nanoparticles in carbonized chitosan aerogel (CCA) not only promotes the self-assembly of CCA and MOF, but also etched Co ions can participate in the growth of MOF, resulting in excellent electrochemical performance. Specifically, the specific capacitance of CCA-Co@MOF reaches 1877.2 F g−1, which is much superior to CCA-M@MOFs (M = Ni, Zn and Cu) and other contrast materials. Furthermore, the asymmetric supercapacitor (CCA-Co@MOF//AC ASC) assembled using CCA-Co@MOF and activated carbon (AC) electrodes, exhibits a high energy density (45.9 Wh kg−1 at 431.7 W kg−1). This work highlights the advantages of metal nanoparticle-modified and carbonized chitosan aerogels for MOF growth, demonstrating its great value in the field of electrochemical energy storage.

Free-Standing, Self-Doped Porous Hard Carbon: Na-Ion Storage with Enhanced Initial Coulombic Efficiency.

The use of porous hard carbons (PHCs) as electrode materials in sodium-ion batteries has great potential; however, the exposure of large surface areas to electrolyte flow results in irregular and irreversible solid electrolyte interfaces (SEIs), leading to deteriorated ionic and electronic mobility and inferior initial Coulombic efficiency (ICE). These issues can be addressed through suitable structural modifications of PHC materials. Herein, the integration of high-surface-area PHCs with carbon nanofibers (CNFs) was accomplished by a simple electrospinning technique, which resulted in a uniform and reversible SEI layer. In the meantime, the CNFs' mesh provided connectivity and conductivity in the as-integrated electrodes, whereas PHCs offered fast diffusion kinetics and high Na+ ion storage capacity. Additionally, PHC integration with CNFs demonstrated an excellent ICE of 77% and a specific capacity of 505 mAh/g at 25 mA/g. Furthermore, the conjugated microstructure also provided flexibility and stability to the electrode (260 mAh/g after 500 cycles). This remarkable synergy may promote the development of free-standing, flexible, and highly porous properties in a single material for advanced energy storage applications.